First, it's based on microkernel architecture, which allows to assemble 'from blocks' different modifications of the operating system depending on a customer's specific requirements.

Second, there's its built-in security system, which controls the behavior of applications and the OS's modules. In order to hack this platform a cyber-baddie would need to break the digital signature, which - any time before the introduction of quantum computers - would be exorbitantly expensive.

Third, everything has been built from scratch. Anticipating your questions: not even the slightest smell of Linux. All the popular operating systems aren't designed with security in mind, so it's simpler and safer to start from the ground up and do everything correctly. Which is just what we did.